25,088 research outputs found

    Inclusive inelastic scattering of heavy ions and nuclear correlations

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    Calculations of inclusive inelastic scattering distributions for heavy ion collisions are considered within the high energy optical model. Using ground state sum rules, the inclusive projectile and complete projectile-target inelastic angular distributions are treated in both independent particle and correlated nuclear models. Comparisons between the models introduced are made for alpha particles colliding with He-4, C-12, and O-16 targets and protons colliding with O-16. Results indicate that correlations contribute significantly, at small momentum transfers, to the inelastic sum. Correlation effects are hidden, however, when total scattering distributions are considered because of the dominance of elastic scattering at small momentum transfers

    An optical model description of momentum transfer in heavy ion collisions

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    An optical model description of momentum transfer in relativistic heavy ion collisions, based upon composite particle multiple scattering theory, is presented. The imaginary component of the complex momentum transfer, which comes from the absorptive part of the optical potential, is identified as the longitudinal momentum downshift of the projectile. Predictions of fragment momentum distribution observables are made and compared with experimental data. Use of the model as a tool for estimating collision impact parameters is discussed

    PILOT: design and capabilities

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    The proposed design for PILOT is a general-purpose, wide-field 1 degree 2.4m, f/10 Ritchey-Chretien telescope, with fast tip-tilt guiding, for use 0.5-25 microns. The design allows both wide-field and diffraction-limited use at these wavelengths. The expected overall image quality, including median seeing, is 0.28-0.3" FWHM from 0.8-2.4 microns. Point source sensitivities are estimated.Comment: 4 pages, Proceedings of 2nd ARENA conference 'The Astrophysical Science Cases at Dome C', Potsdam, 17-21 September 200

    Interpolation of the Josephson interaction in highly anisotropic superconductors from a solution of the two dimensional sine-Gordon equation

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    In this paper we solve numerically the two dimensional elliptic sine-Gordon equation with appropriate boundary conditions. These boundary conditions are chosen to correspond to the Josephson interaction between two adjacent pancakes belonging to the same flux-line in a highly anisotropic superconductor. An extrapolation is obtained between the regimes of low and high separation of the pancakes. The resulting formula is a better candidate for use in numerical simulations than previously derived formulas.Comment: 18 pages, 9 figure

    Supersymmetry without a Light Higgs Boson

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    Motivated by the absence, so far, of any direct signal of conventional low-energy supersymmetry, we explore the consequences of making the lightest Higgs boson in supersymmetry relatively heavy, up to about 300 GeV, in the most straightforward way, i.e. via the introduction of a chiral singlet S with a superpotential interaction with the Higgs doublets, \lambda S H_1 H_2. The coupling \lambda dominates over all the other couplings and, to maintain the successful perturbative analysis of the ElectroWeak Precision Tests, is only restricted to remain perturbative up to about 10 TeV. The general features of this "\lambda SUSY" framework, which deviates significantly from the MSSM or the standard NMSSM, are analyzed in different areas: ElectroWeak Precision Tests, Dark Matter, naturalness bounds on superparticle masses, and LHC signals. There is a rich Higgs/Higgsino sector in the (200-700)GeV mass region, which may include LSP Higgsino dark matter. All other superpartners, apart from the top squarks, may naturally be heavier than 1-2 TeV. This picture can be made consistent with gauge coupling unification.Comment: 27 page

    Submergence and uplift associated with the giant 1833 Sumatran subduction earthquake: Evidence from coral microatolls

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    The giant Sumatran subduction earthquake of 1833 appears as a large emergence event in fossil coral microatolls on the reefs of Sumatra's outer-arc ridge. Stratigraphic analysis of these and living microatolls nearby allow us to estimate that 1833 emergence increased trenchward from about 1 to 2 m. This pattern and magnitude of uplift are consistent with about 13 m of slip on the subduction interface and suggest a magnitude (M_w) of 8.8–9.2 for the earthquake. The fossil microatolls also record rapid submergence in the decades prior to the earthquake, with rates increasing trenchward from 5 to 11 mm/yr. Living microatolls show similar rates and a similar pattern. The fossil microatolls also record at least two less extensive emergence events in the decades prior to 1833. These observations show that coral microatolls can be useful paleoseismic and paleogeodetic instruments in convergent tectonic environments

    Molecular Dynamics of pancake vortices with realistic interactions: Observing the vortex lattice melting transition

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    In this paper we describe a version of London Langevin molecular dynamics simulations that allows for investigations of the vortex lattice melting transition in the highly anisotropic high-temperature superconductor material Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta}. We include the full electromagnetic interaction as well as the Josephson interaction among pancake vortices. We also implement periodic boundary conditions in all directions, including the z-axis along which the magnetic field is applied. We show how to implement flux cutting and reconnection as an analog to permutations in the multilevel Monte Carlo scheme and demonstrate that this process leads to flux entanglement that proliferates in the vortex liquid phase. The first-order melting transition of the vortex lattice is observed to be in excellent agreement with previous multilevel Monte Carlo simulations.Comment: 4 figure

    Heat capacity mapping mission project HCM-051

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    There are no author-identified significant results in this report

    Evolution of Fermion Pairing from Three to Two Dimensions

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    We follow the evolution of fermion pairing in the dimensional crossover from 3D to 2D as a strongly interacting Fermi gas of 6^6Li atoms becomes confined to a stack of two-dimensional layers formed by a one-dimensional optical lattice. Decreasing the dimensionality leads to the opening of a gap in radio-frequency spectra, even on the BCS-side of a Feshbach resonance. The measured binding energy of fermion pairs closely follows the theoretical two-body binding energy and, in the 2D limit, the zero-temperature mean-field BEC-BCS theory.Comment: 5 pages, 4 figure
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